Lubricating oil composition



Patented Nov. 21, 1939 Arnold fivobaclawhitinmlnda a-ignor 'elairluiiningcompannflew'lorbltiaa eorporaflonoillaine tell!!- it 1mm. Application my :7. 1m.

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20laima( My invention relates to improvements in liquid compounded petroleum lubricating oils. The term "petroleum lubricating oils" is intended to reier herein to lubricating oils of petroleum origin 5 having viscosities upwards of 50-70 seconds at 100 1''. Baybolt Universal.-

The improved liquid lubricating oil compositions 01 my invention consist essentially of a.

, petroleum lubricating oil having dissolved therein a stannous aromaticstearate 'such as stannous phenyl stearate. The composition may also include other metallic aromatic stearates and other metallic stearates, and an aromatic stearic acid,

, stearic acid or palmitic acid. The aromatic ll stearic acids useful for the purposes 01' my invention include phenyl stearic acid, tolyl stearic acid, xylyl stearic acid, naphthyl stearic acid and anthracyl stearic acid. The addition of such stannous soaps, or other metallic soaps, and free acids m should bemade in amount or amounts i'nsuflicient materially to alter the normally liquid characterof the petroleum lubricating oil itself, for example, from 0.5%-2.5% on the oil.

The trend of development in internal combus- 35 tion engines has imposed increasing burdens upon the oils used for their lubrication, particularly with respect to operating temperatures and pressures. -At present, the Diesel type of engine probably represents extreme requirements 'in 130 both or these respects, but it is not alone in the imposition of severe burdens upon the lubricating .oil used. The useful operating life of a lubricating oil, in such service, isdetermined, in large measure, by its thermal stability and by its phys- 35 ical capacity to continue functioning as a lubricant, at the high temperatures and high pressures encountered. One measure of thermal stability is resistance to oxidation, and the consequent tendency to form sludge, but in another aspect the 40 eilect of thermal instability is determined not only by the extent of oxidation or decomposition but also by the character of the products of such decomposition or oxidation and by the extent and location, within the engin of deposits of such 45 products.

The improved lubricating oil compositions 01 my invention have, in addition to the lubricating properties of the petroleum oils of which they are compounded, a high solvent capacity for sludge,

so of the character formed by oxidation of petroleum'lubricating oils, and, perhapsoi even greater importance, the properties of rendering deposits of sludge and carbon" within the engine soft and i'riable rather than hard and coherent and of disss integrating and removing such deposits as an incident or the normal operation of the engine. In this t, the lubricating oil compositions of my invention render the engines in which they areused selicleaning to an important extent.

In the Diesel type of engine, forexample, the 5 high temperatures to which the lubricating oil is subjected, particularly at the top of the stroke, frequently cause deposition of sludge and carvbon'ization in the groove for and behind one oi more of the piston rings. Using parafllnic type 10 lubricating oils such dimculties are usually more pronounced with respect to the uppermost ring; using naphthenic type lubricating oil they are usually more pronounced with respect to the lower rings. consequent sticking of the rings rapidly deprives the piston and cylinder wall of proper lubrication inducing excessive wear and, frequently, scoring of the cylinder wall. The formation of such "carbon deposits, hard enough and coherent enough to involve stickingoi the rings, is materially retarded, it not avoided, by the use oi the improved lubricating oil compositions of my invention, and in this aspect the self-cleaning properties or the lubricating oil compositions of my invention, with respect to the engine, make a mere 'change of oil a substitute, economical with respect both to loss of service time and cost, for

many otherwise necessary cleaning and repair jobs.

Stannous phenyl stearate, or mixtures including stannous phenyl stearate and stannous stearate, for compounding the improved lubricating oils or my invention, can be produced as follows:

1 part (parts by weight) of pulverulent anhydrous aluminum chloride is stirred into 4 parts of commercial benzol boiling below 0., this stirring being effected at atmosphericpressure and at ordinary temperature. 2 parts oi oleic acid, commercial red oil containing as a minimum 96% free fatty acid as oleic acid and 40 having a maximum cloud test 01 45? F., is added to this mixture with stirring, the addition being made over a period of about an hour. This reaction is carried out at atmospheric pressure and is started at ordinary temperature. The tempera- 45 ture rise incident to the reaction is limited so that the maximum temperature approximates 180, F., the temperature being controlled either by cooling or by regulating the rate of addition of the oleic acid. The reaction mixture is maintained 5 at'a temperature of -180 F. for 6 or 7 hours. For at least the last half hour of this period the reaction mixture is held at F. to insure completion of the reaction and to assist in stripping hydrochloric acid from the reaction mixture. 55

The reaction product, a pasty liquid, is then added to about A, to V of its volume of aqueous hydrochloric acid, 15% to 20% HCl, at ordinary temperature. The ensuing reaction brings the temperature, for example, to about 170 F. This reaction mixture is thoroughly stirred and'the aqueous acid solution is then separated from the oily product of the reaction, by decantation for example. This separated oily product is thoroughly washed with water, advantageously with hot water, in two successive stages with about k of its volume of hot water in each stage for example. This washing should in any event be continued until a qualitative test for aluminum in the wash water is negative. After this washing, the reaction product is a thin, oily, dark green liquid. It is allowed to stand to settle out any remaining water. Benzol is stripped from this oil liquid by distillation, limiting the maximum liquid temperature to about 350 F., using steam or other distillation medium to effect the stripping within this maximum temperature limit. The oily liquidv remaining after stripping of benzol is then subjected to distillation, advantageously under a high vacuum, 2-4 millimeters of mercury absolute pressure for example. This distillation may be otherwise efiected, using steam or other distillation medium for example, provided the material undergoing distillation is not heated to any temperature much exceeding 640-650 F. for any period long enough to involve decomposition. When effecting the distillation under a vacuum of 4 millimeters of mercury absolute pressure, a first cut of about 25% is taken off up to the point at which the temperature of the liquid in the still reaches 466 F. and a second cut of about 53% is taken oi as the temperature of the liquid in the still rises from 466 F. to 590 F. The stannous phenyl stearate being added in suflicient excess not only to precipitate but also to coagulate the stannous phenyl stearate. The aqueous solution is decanted from the insoluble stannous phenyl stearate which is then washed thoroughly with water and there- 'stearate and stannous stearate.

above is stannous phenyl stearate" as that f term is used herein, although I intend to refer to this same material by whatever process it may be made. duct which results it the first distillate fraction as well as the second is saponifled and precipitated as described is a mixture of stannous phenyl In compounding the improved liquid lubricating oil compositions of my invention with the usual petroleum lubricating oils, the stannousphenyl stearate. or the mixture of stannous phenyl stearate and stannous stearate, produced as described above, are added to the lubricating oil in proportions ranging from about 0.5% up to about 2.0% or 2.5% by weight on the oil. A composition consisting chiefly of a South Texas pale oil having a viscosity of 500 seconds at 100 F. Saybolt Universal and boiling approximately 10% up to 700 F. and 90% up to 900 F. and 1.33% by weight .on the oil of a mixture of stannous phenyl stearate and stannous stearate is particularly advantageous. The Indiana oxidation test, described in the S. A. E. Journal 34, 172-173 (1934) on one such composition containing stannous phenyl stearate was 18.5 hours, the corresponding value for the lubricating oil alone being 13.5 hours. This same lubricating oil composition, when exposed to highly heated surfaces, decomposed to produce a residue consisting of a soft friable coke in contrast to the hard and adherent residue resulting when the lubricating oil alone was so exposed.

Any tendency of the stannous phenyl stearate abnormally to increase the viscosity of the oil to which it is added may be reduced by the addition of a smallamount of free phenyl stearic acid, free stearic acid or tree palmitic acid. In a lubri- Also, the major portion of the proeating oil composition such as that specifically described above, for example, the addition of 7%*8% of the acid, based on the soap, is eflectlve for this purpose, although proportions up to about 20% are sometimes advantageous.

I claim:

1. A liquid lubricating oil composition comprising a petroleum lubricating oil and stannous phenyl stearate.

2. A liquid lubricating oil composition comprising a petroleum lubricating oil and a stannous aromatic stearate.

' ARNOLD C. VOBACH. 

